The invention relates to a rotor shaft of a spinning rotor and, more particularly, to a spinning rotor shaft with an annular magnetic bearing component, secured with respect to the centrifugal force effective during the spinning process by a ring liner, for radially and axially supporting the rotor shaft, and wherein the rotatable magnetic bearing component interacts with a stationarily arranged magnetic bearing component.
In conjunction with open end rotor spinning machines, spinning rotors and their bearing are known in various embodiments and described in detail in the patent literature. Spinning rotors of this type, as is known, run at a high speed during the spinning process in a rotor housing which is acted upon by reduced pressure. The majority of open end spinning machines in the market have spinning rotors, which are mounted by their rotor shaft in the bearing interspaced of a so-called support disc bearing arrangement. In the case of support disc bearing arrangements of this type, which allow rotor speeds>100,000 rpm, it is conventional to provide an additional axial bearing, which can be configured either as a mechanical bearing or as a magnetic bearing, for axial fixing of the spinning rotor.
Even if these support disc bearing arrangements have been successful in practice, they have the disadvantage that the support discs are mechanically substantially stressed, in particular in the region of their contact surfaces. The milling work occurring in these regions leads not only to not insubstantial wear of the contact coverings of the support discs, but also to power losses.
In the past, various attempts have been made to mount spinning rotors circulating at a high speed without wear.
German Patent Publication DE 198 27 606 A1 describes, for example, single motor driven spinning rotors, which are contactlessly supported in corresponding magnetic bearing arrangements. These magnetic bearing arrangements, in each case have an annular permanent magnet both on the stator side and on the rotor side. The permanent magnets are arranged in this case such that repelling magnetic bearing forces are effective between the rotor magnets and the stator magnets.
Provided in the region of the permanent magnets of the stator are also electrical windings, by which, as a function of the electrical current flow direction, the magnetic force of the stator magnets can be reinforced or lowered. The electrical windings are activated in this case via a corresponding control device as a function of signals of a sensor, which detects the axial deviation of the rotor shaft of the spinning rotor from its desired position, for example.
In the magnetic bearing arrangement according to German Patent Publication DE 198 27 606 A1, as already indicated above, the permanent magnets circulating with the spinning rotor are annular and let into cover elements, which are in turn connected in a rotationally engaged manner to the rotor shaft of the spinning rotor. This type of fixing of the permanent magnets rotating at a high speed was not satisfactory; there has now been a change to drawing the annular permanent magnets of the rotor onto bearing lugs of special receivers and securing the drawn-on permanent magnets with an external ring liner against the centrifugal forces occurring during the spinning operation. The special receivers for the permanent magnets are fixed here so as to be rotationally engaged on the rotor shaft.
With regard to drawing the annular permanents magnets onto the bearing lug of a receiver of this type and their securing by ring liners, until now two different methods were conventional. In other words, the ring magnets were either slipped with play onto the bearing lug of the receiver and then locked by a ring liner, the internal diameter of which was below the external diameter of the ring magnet, or the ring liners were initially fixed onto the ring magnets by means of a press fit and the surrounded ring magnets were then pressed, also by means of a press fit, onto the bearing lug of the associated receiver.
In the two methods, the diameter of the connection faces had to have very exacting tolerances, as there was otherwise the risk of damage to the relatively sensitive ring magnets during the pressing-on processes. The described methods proved to be not very effective overall, as despite exacting tolerances, damage to ring magnets during pressing on could not always be avoided. In other words, in the known manufacturing methods, the waste quota was relatively high.